title: Near-Infrared High Resolution Diode Laser Spectrum of the CH2 &btilde;1B1 <-- &atilde;1A1 Transition
abstract: A new diode laser-based spectrometer operating at wavelengths close to 1 &mgr;m has been constructed for transient absorption measurements in the gas phase. Using a dual beam detection system for noise cancellation, the minimum detectable absorption was found to be 1 x 10(-4) in 0.5 &mgr;sec. The sensitivity of the instrument is illustrated by the observation of previously undetected spectra of singlet methylene (CH2) between 9780 and 10070 cm-1. Rovibronic transitions involving two Ka = 1 levels, nominally associated with v2(bent) = 1 and 2, in the upper, &btilde;1B1, state have been assigned. These levels are the lowest so far observed for methylene in this electronic state and their positions provide new information on the shape of the bending potential for the molecule at energies approaching that at which the two lowest singlet states (&atilde;1A1 and &btilde;1B1) of the molecule become degenerate at the linear configuration. Copyright 1998 Academic Press. Copyright 1998Academic Press
authors.affiliation: Department of Chemistry, Brookhaven National Laboratory, Upton, New York, 11973-5000
authors.initials: C
authors.lastname: Fockenberg
authors.initials: AJ
authors.lastname: Marr
authors.initials: TJ
authors.lastname: Sears
authors.initials: BC
authors.lastname: Chang